Many devices have operating systems that control their function. For example, computers, cell phones and handheld devices can have different kinds of operating systems. With some categories of devices, such as a personal computer, the user can have the ability to choose between operating systems available from different manufacturers. As another example, a user currently using an operating system may want to upgrade to a more recent version of that operating system.
Thus, there are several reasons why a user might consider obtaining an operating system for the device, whether it be the first operating system ever installed on the device or a replacement for an existing operating system. The choice among several operating systems necessarily takes into account device compatibility, but can also be based on other factors, such as the functions they offer, their usability and reliability, and also the cost of obtaining and maintaining the operating system.